Fiber opening roll of an open end spinning device

ABSTRACT

The spinning roll and housing are constructed to define a small laterally extending clearance which communicates the annular space between the clothing on the roll and the inside surface of the housing with a space of higher pressure. The clearance acts as a pneumatic seal to prevent lateral outward passage of fibers from the housing while, at the same time, allowing sufficient air to pass into the housing to ensure against too large an ingress of air at the waste separation opening.

United States Patent 1191 Schiltkneeht Apr. 2, 1974 FIBER OPENING ROLLOF AN OPEN END 3,455,097 7/1969 Rajnoha et al 57/5895 SPINNING DEVICE3,626,681 12/1971 Naruse 57/5895 X 3,434,184 3/1969 Doudlebsky et a].57/589] ux [75] Inventor: Adolf Schiltknecht, Winterthur,

Switzerland [73] Assignee: Rieter Machine Works, Ltd.,

Winterthur, Switzerland [22] Filed: June 4, 1973 [21] App]. No.: 366,525

521 US. Cl. 57/58.9l [51] Int. Cl D0lh 1/12 [58] Field of Search57/58.8958.95

[56] References Cited UNITED STATES PATENTS 3,624,997 12/1971 Didek etal. 57/5891 3,624,995 12/1971 Rajnoha et al 57/5891 PrimaryExaminerDonald R. Watkins Attorney, Agent, or FirmKenyon & Kenyon ReillyCarr & Chapin [5 7 ABSTRACT The spinning roll and housing areconstructed to define a small laterally extending clearance whichcommunicates the annular space between the clothing on the roll and theinside surface of the housing with a space of higher pressure. Theclearance acts as a pneumatic seal to prevent lateral outward passage offibers from the housing while, at the same time, allowing sufficient airto pass into the housing to ensure against too large an ingress of airat the waste separation opening.

25 Claims, 11 Drawing Figures PAIENIEBarn 2 I974 I SHEU 1 BF 2 FIG. 9

FIBER OPENING ROLL OF AN OPEN END SPINNING DEVICE This invention relatesto a fiber opening roll of an open end spinning device.

As is known, open end spinning devices have used fiber opening rolls foropening a staple fiber sliver into individual fibers which subsequentlyare transferred into a spinning rotor for twisting into a yarn. In someinstances, the opening roll has been equipped wih a clothing (needles orclothing wire provided with points) and mounted in a housing or a sleevewhich is closed on all sides. The housing has usually had a fiber feedpoint and a fiber transfer duct for guiding the fibers into the spinningrotor after leaving the clothing of the opening roll. The housing orsleeve has also been provided with lateral covers arranged in very closeproximity to the face sides of the opening roll in order to concentratethe air flow into the annular space immediately around the clothing. Inpractical use, however, it was found that a small airstream flows alongthe face sides of the opening roll, as a pressure differential prevailsbetween the fiber feed point and the entry into the fiber transfer duct.This small airstream can indeed carry on fibers leaving the clothinglaterally. Thus, agglomerations of these fibers in the narrow face sideclearance space frequently occur. Eventually, these agglomerations havereached the fiber transfer duct in the form of bundles or lumps which,once spun into the yarn, result in undersirable thick places in theyarn. Due to the necessarily small clearances at the face sides of theopening rolls, such fiber agglomerations or accumulations frequentlycause varying braking of the opening roll and, in extreme cases, theopening rolls have been blocked entirely.

If elimination of these symptoms is attempted, e.g., by furthernarrowing the clearances at the face sides, this would involve othersevere disadvantages. For example, the axial position of the openingroll would have to be maintained very exactly in order to avoid anygrinding contact of the opening roll face sides on the correspondinglateral wall of the housing or cover. Maintenance of the axial positionwithin very small tolerances would also require the use oflongitudinally pretensioned bearings of zero axial play which, at thehigh rotational speeds of 5000 to 8000 rpm. of opening rolls, cause verysubstantial premature wear. Also, a tendency of lap formation on thedrive shaft of the opening roll would be observed, particularly in casethe bearing is arranged adjacent to, or in close vicinity of, theopening roll housing for design reasons, so that lubricants can creepalong the drive shaft into the housmg.

Attempts have been made to keep the negative effects of the vacuum awayfrom the opening roll face side space, which effects would otherwiseassist the fibers leaving the clothing laterally, by providing air inletopenings in the walls covering the face sides, or in the coversrespectively. These openings allow air to be sucked in and thrownradially towards the outside with air transporting grooves, acting as afan, also being provided on the periphery of the roll. Such measures,however, cannot be very effective, as the increased quantity of air,moved at the expense of additional power consumption exceeds thesucking. capacity of the space beteen the clothing and the housing aswell as of the adjacent rotor. This quantity of air cannot be increasedwithout inducing other disadvantages.

Accordingly, it is an object of the invention to effectively preventfibers from leaving a clothing of an opening roll laterally withoutaffecting the technologically optimal air throughput quantity at theopening roll and without exaggerated requirements for the opening rollbearings.

It is another object of the invention to construct an opening roll insuch a manner that the housing for the roll need not be closed by a wallor a cover so that easy lateral removal is possible.

It is another object of the invention to construct an opening roll insuch a manner that the bearing side as well the opposite non-bearingside of the opening roll can be mounted in a housing without lateralcovers.

It is another object of the present invention to ensure that nodetrimental fiber accumulations can form on an opening roll not coveredon one side.

It is another object of the invention to eliminate as far as possiblethe influence of fan action of an opening roll onto the air throughputof the opening roll.

Briefly, the invention provides a fiber opening roll for an open endspinning device, which cooperates with a housing to define a pneumaticsealing clearance extending laterally of the confines of the housing.The roll is rotatably mounted in the housing and is provided with aperipherally mounted clothing thereon. The housing, in turn, has a firstsurface which cooperates with the clothing to define an annular spacefor guiding an air stream under vacuum from a fiber feed point past awaste separation point to a fiber transfer duct. The clearance is formedat at least one side of the clothing by a second surface of the housingand a peripheral surface of the roll which extends laterally from theclothing.

The housing is formed so that the fiber feed point, waste separationpoint and transfer duct each communicates the inside of the housing withthe exterior of the housing so that air can pass into and through thehousing under a suction force created, e.g., by a rotor, downstream ofthe transfer duct. I

The clearance between the roll and the housing may take various formssuch as cylindrical or conical and may be defined by smooth orinterrupted surfaces as by a stepped configuration or a recessedconfiguration. In addition, the clearance is sized to prevent ingress offibers laterally from within the housing while, at the same time,allowing sufficient air to pass into the housing to ensure against toolarge an ingress of air at the waste separation point. To this end, theradial size of the clearance is of from 0.3 millimeters (mm) to 0.5millimeters (mm) while the width b is less than d /a k wherein d is thediameter of the surface of the roll, a is the working width of theclothing and k a constant of from 0.02 to 0.12. Depending on the type ofclothing used, k may vary from 0.02 to 0.12 for rolls with anunperforated clothing or 0.09 to 0.12 for a clothing made up ofindividual rods which support radial needles.

These and other objects and advantages of the invention will become moreapparent from the following detailed description and appended claimstaken in conjunction with the accompanying drawings in which:

FIG. 1 illustrates a view taken on line Il of FIG. 2 of a housing andopening roll according to the invention;

FIG. 2 illustrates a view taken on line Il-Il of FIG. 1;

FIG. 3 illustrates a cross-sectional view of an opensided housing withan opening roll composed of circumferentially spaced rods constructedaccording to the invention;

FIG. 4 illustrates a cross-sectional view of a further modifiedstructure according to the invention;

FIG. 5 illustrates a view of an embodiment of the invention utilizing aconical sealing clearance;

FIG. 6 illustrates a view of another embodiment of the inventionutilizing a clearance of stepped configuration;

FIG. 7 illustrates a labyrinth type of clearance according to theinvention;

FIG. 8 illustrates a plan view of an eccentrically mounted roll within ahousing according to the invention;

FIG. 9 illustrates a cross-sectional view of a modified clearanceaccording to the invention;

FIG. 10 illustrates a roll having a grooved sealing surface according tothe invention; and

FIG. 11 illustrates a cross-sectional view of a clearance which iswithin the plane of the clothing in accordance with the invention.

Referring to FIGS. 1 and 2, the open end spinning device substantiallyconsists of a cup-shaped housing 1 in which an opening roll 2 isrotatably arranged. The roll 2 is provided at the periphery with aclothing 3 of needles or points. Fibers are supplied to the roll 2 inthe form of a fiber sliver 5 via a fiber feed opening 4 in the housingI. The clothing 3 is spaced from a cylindrical inside surface 8 of thehousing 1 to define an annular space 7 so that individual fibers whichare detached from the sliver 5 by the points of the clothing 3 can becarried on until reaching a fiber transfer duct 9 leading from theinterior of the housing 1 into a space in which a spinning rotor (notshown) is arranged and in which a vacuum prevails. The housing 1 alsocontains a waste separator opening 10 between the feed roll 6 and thefiber transfer duct 9 through which air can be drawn into the space 7and added to the air taken in via the opening 4. The periphery of theroll 2, as shown at the left hand side, is provided with an axiallyextending rim 12, the outside surface 13 of which in combination with aninside surface 13' of the surrounding housing 1 forms a small annularclearance 14 which communicates the inside of the housing 1 with thespace of atmospheric pressure p This clearance 14 is of a radial width,e.g., for roll diameters in the range of about 60 to 70 millimeters (mm)of at least 0.3 millimeters (mm), and as a rule, about 0.5v millimeters(mm). Smaller clearances cannot be considered due to manufacturingreasons.

During operation, air flows from the opening 4 via the space 7, in whicha subatmospheric pressure prevails, to the duct 9. As shown, the housing1 on the left hand side is not enclosed and, thus, atmospheric pressure2,, prevails on the face side of the roll 2.

Depending on the speed at which the air is taken in via the wasteseparator opening 10, more or less waste and short fibers areeliminated. That is, the waste and fiber particles loosened bycentrifugal force and by an edge 11 (FIG. 1) of the opening 10 move inopposition to the air flowing into the opening 10 towards the inside ofthe housing 1. If the air speed at this place is too high, the particlesare taken back into the fiber flow flowing in space 7.

The throughput quantity of the air flowing from the outside of thehousing 1 towards the inside of the housing 1 can be influenced bysuitably chosing the width b of the clearance 14. Investigations haveshown that an advantageous relation for chosing the width of theclearance 14 roughly is:

where d is the diameter of the surface 13 of the roll 2, a the width ofthe active part of the roll periphery, i.e., the working width of theclothing 3 and k is a constant depending on the construction of the roll2. The ranges of values of k are:

2/109 a l i927... i.e., 0.02 to 0.12 for rolls of unperforated clothingsupport surface according to FIG. 1, and

i.e., 0.09 to 0.12 for rolls, the clothing of which consists ofindividual rods supporting radial needles 18 (FIG. 3), which rods areuniformly distributed along the circumference of the face side walls ofthe roll.

It can be seen that if the width of the clothing zone is large (i.e.,ifa is large) the width b of the clearance 14 can be chosen smaller,i.e., that more air may enter from the outside. That is, by using alarge clothing, a large quantity of air is transported in thesurrounding annular space 7 (FIG. 1) so that the air quantitypenetrating via the clearance 14, and added, may also increase withoutseverely affecting the air throughput conditions. The connection of theclearance 14 with the space in which the atmospheric pressure p,,, andthus a higher pressure than in the space 7 (pressure p,-), prevailsis ofgreat importance. This is because a determined small air current fromthe outside to the inside is created, which not only prevents the fibersfrom leaving the clothing laterally and penetrating into the clearance14, but also ensures that no excessive air quantitites are sucked in viathe opening 10 which would otherwise cause, amongst other effects, adeterioration of the waste separation.

The intake of excessive quantities of air to the opening roll 2 via theclearance 14 can cause a reduction of the air intake via the wasteseparator opening 10. In such a case, too many good fibers can flyagainst the weakened countercurrent of air in the opening 10 and can beeliminated. Also, if the clearance 14 is too wide, too high a pressurecan result at the opening 4 of the feed point, so that fibers can leaveand cause undesirable fly. Accordingly, a correct choice of thedimensions of the sealing clearance 14 is thus of decisive importancefor good performance of the opening roll 2 and of the waste separatoropening 10.

As shown in FIG. 1, the provision of a sealing clearance 14 on one sideonly is entirely sufficient, as small air quantities are sufficient toinfluence the air throughput conditions as desired. The housing 1 isleft open on the side of the bearing 18, and on the opposite side theroll 2 is completely surrounded by the housing 1. The bearing 18maintains the axial position of the roll 3. The support of the bearing18 is constructed in such a manner that enough passage space isavailable for the air under atmospheric pressure p,, to reach the entryof the clearance 14 without obstacles. The critical fly and dustconditions usually found at the bearing caused by currents through thebearings are eliminated in this manner, as atmospheric pressure prevailson both sides of the bearing 18.

Referring to FIG. 4, the roll housing can be open at both ends. Thisimplies the requirement of larger rims in order to keep the quantitiesof air entering within the limits required. As shown, also, the roll isconstructed of a plurality of circumferentially spaced rods 16, each ofwhich carries radiating pins 17. Also, a sealing clearance is formed oneach side of the roll 15 in cooperation with the housing.

Referring to FIG. 5, the air throughput conditions of the opening rollalso can be influenced by the position of the sealing clearance. Thus,as shown, the surfaces forming the sealing clearance are conical so thatunder the same pressure differential somewhat less air flows through theclearance 20 towards the inside than in a cylindrical arrangement. Theclearance additionally converges somewhat towards the inside, the coneagnle of the housing 21 being ,8 and the cone angle of the roll 22 beinga where a is less than B. This ensures the technological advantage that,at the same mean clearance width, the air speed is maximum at the exitto the clothing so that the danger of fiber penetration into theclearance 20 is reduced.

Referring to FIG. 6, a clearance 23 can also be formed in step form. Inthis case, the widths of the axial zones 24 and 25 are very narrow andthe radial intermediate zone 26 is much larger due to the longitudinalplay of the bearing (not shown). Further, for mounting spacerequirements, a labyrinth sealing effect is I achieved which improvesthe sealing effect. The sealing effect, of course, can be furtherincreased if a multiple labyrinth sealing is chosen, as shown in thesymmetrical construction shown in FIG. 7 wherein like referencecharacters indicate like parts as above. In this latter case, eachsealing surface 13 is interrupted by a pair of circumferential grooves27.

A further means of influencing the air throughput quantities flowingthrough the clearance towards the inside is the chosing of suitablediameters. In the arrangement according to FIG. 5, the clearance 20merges into the inside space at the outside diameter of the openingroll, i.e., at the base of the clothing. In the arrangement shown inFIGS. 1, 2, 6 and 7, each clearance projects into the space radiallyoutside the outside diameter of the clothing, i.e., at the circle ofpoints of the clothing. In the arrangement according to FIG. 11, theclearance projects about at the midpoint between the base and the circleof points of the clothing.

In view of the fact that the same pressure does not prevail at all theplaces along the circumference of an opening roll, the pressuredifferential between the outside space (under atmospheric pressure p,,)and the inside space above the cothing or the roll (under the lowerpressure P) can be influenced locally at a determined place along thecircumference or over a determined portion of the circumference. To thiseffect, the roll 27 (FIG. 8) can be arranged eccentrically with respectto the housing inside surface 28, the eccentricity being 2. In this way,a maximum clearance width S maximum between the housing inside wall 28and the outer rim 29 of the roll results. This clearance width isreduced over half the roll circumference to S minimum.

Alternatively, as shown in FIG. 9, the sealing effect can be varied onlyover a determined portion of the circumference. For example, theclearance 30 is enlarged along the circumference of the housing 3 overan angular sector B. Also, a labyrinth arrangement which extends onlyover a sector of the circumference can be possible.

Referring to FIG. 10, the surface rim forming the clearance 32 togetherwith the housing 33 can also be provided with grooves 34 which, withrespect to a given sense of rotation of the roll (indicated by an arrow)are directed towards the outside. If a very small angle y is chosen, ahelix extending over the full circumference of the roll is created. If alarge angle 3 is chosen, a short groove 35 only is created as indicatedwith dashdotted lines. The depth of the groove 35 can be chosen so as todecrease towards the inside. In the first case, two advantages result.On the one hand, a labyrinth type seal with improved sealing effects isachieved, and on the other hand, any fibers which penetrate from theclothing to the clearance, in spite of the air flow, tend to betransferred back. In the second case, only the fibers are transferredback.

In order to prevent the formation of fiber accumulations at the sideopposite the open side where the clearance arrangement is provided,precautions are taken there to reduce the space between the clothing andthe adjacent corner of the housing without detrimentally influencing theair throughput conditions of the roll. As air also flows between theface side of the roll and the housing wall, which can carry fibers,precautions are to be taken to ensure that such fibers can move backinto the normal flow of fibers without meeting obstacles. For example,in order to prevent clinging of fibers in the housing corner, the cornerspace not acted upon by the clothing is reduced, as shown in FIG. 1, byproviding an inclined corner 36. Alternatively, as shown in FIG. 5, arounded corner 37 can be provided with the outermost points 38 of theclothing inclined towards the outside The cross-sectional area of awidth of about 0.5 millimeters (mm), if roll diameters ranging from 60to millimeters (mm) are used, remains unchanged in these arrangements.

Similarly, as shown in FIG. 6, the corner not acted upon by the clothingcan be reduced by providing a protrusion 40 of the housing to reach intoclose proximity to the outermost points 41 of the clothing. A furtheralternative is shown in FIG. 11, in which the corner is reduced by meansof a conical portion 42 of the housing wall and by an inclined rim 43 ofthe roll which is adapted to the conical portion 42. In this case,however, the diameter of the rim 43 is chosen noticeably smaller thanthe one of the circle of the points of the clothing so that the fiberscan easily move onto the clothing.

The present invention results in a number of substantial advantages.Manufacturing, assembling and checking in operation are facilitated andmade more economical by the advantageous constructions. In particular,the antifriction bearings can be chosen without longitudinalpretensioning and within normal tolerances. The bearings are also lessexposed to wear, as no lubricatns are drained off laterally.Technological conditions are also markedly improved. in particular,sufficient sealing effects from the outside towards the inside areachieved in spite of the width of the clearance which is not chosenextremely narrow, so that the air intake capacity of the subsequentelements is not exceeded and that the waste extraction is not impaired.Furthermore, the number of ends down is reduced by more than 20 percentand, primarily, a reduction of the dreaded fiber bundle or packetformation down to about one twentieth of the previous level is achieved.As a result, the number of thick places in a processed yarn as well asblocking of the device are reduced dras tically to a practicallyinsignificant level.

What is claimed is: 1. In an opening end spinning device a housinghaving a first cylindrical inside surface, a

seocnd inside surface, a fiber feed point communicating the inside ofsaid housing with the exterior of said housing, a fiber transfer ductcommunicating the inside of said housing with the exterior of saidhousing and a waste separating point between said feed point and saidduct communicating the inside of said housing with the exterior of saidhousing; and a fiber opening roll rotatably mounted in said housing,said roll having a clothing peripherally disposed thereon within saidfirst cylindrical inside surface for combing out fibers from a deliveredsliver, said roll and said first cylindrical inside surface defining anannular space for guiding an air stream under vacuum from said feedpoint past said waste separating point to said transfer duct, said rollhaving a peripheral surface at at least one side of said clothingdefining a laterally extending clearance with said second inside surfaceof said housing to communicate said annular duct with a space of higherpressure. 2. In an open end spinning device as set forth in claim Iwherein said roll has a second peripheral surface on an opposite side ofsaid clothing defining a second laterally extending clearance with afurther inside surface of said housing.

3. In an open end spinning devices set forth in claim 1 wherein saidclearance has a width (b) of b 2 a" k wherein d is the diameter of saidperipheral surface, a is the width of said clothing and k is a constantlarger than 9/1000.

4. In an open end spinning device as set forth in claim 1 wherein saidclearance is cylindrical.

5. In an open end spinning device as set forth in claim 1 wherein saidclearance is conically diposed outwardly from said roll.

6. In an open end spinning device as set forth in claim 1 wherein saidclearance merges with the base of said clothing.

7. In an open end spinning device as set forth in claim I wherein saidclearance extends radially outside said clothing.

8. In an open end spinning device as set forth in claim 1 wherein saidclearance extends intermediately of said clothing.

9. In an open end spinning device as set forth in claim 1 wherein saidclearance includes a plurality oflaterally extending narrow zones and aradially extending wider zone arranged between said narrow zones.

10. In an open end spinning device as set forth in claim 9 wherein thediameters of said laterally extending zones are stepped.

11. In an open end spinning device as set forth in claim 10 wherein saidsecond inside surface is stepped to form said wider zone.

12. In an open end spinning device as set forth in claim 9 wherein saidroll has grooves in a rim thereof forming said wider zone, said groovesextending from the outside towards the inside in opposition to thedirection of rotation of said roll.

13. In an open end spinning device as set forth in claim 12 wherein saidgroove forms a very small angle with respect to the lateral limitationof said roll and extends over at least a substantial part of thecircumference of said roll.

14. In an open end spinning device as set forth in claim 12 wherein saidgroove forms a large angle with respect to the lateral limitation saidroll and extends only over a small fraction of the circumference of saidroll.

15. In an open end spinning device as set forth in claim 1 wherein saidclearance is of variable width.

16. In an open end spinning device as set forth in claim 15 wherein thewidth of said clearance decreases from the outside towards the inside.

17. In an open end spinning device as set forth in claim 15 wherein saidroll is eccentrically mounted with respect to said second inside surfaceto vary the width of said clearance.

18. In an open end spinning device as set forth in claim 15 wherein saidhousing has a recess of circumferentially limited extension to vary thewidth of said clearance.

19. In an open end spinning device as set forth in claim 1 wherein saidhousing has a reduced corner space on the side of said roll opposite tothe side of said clearance.

20. In an open end spinning device a housing defining a first insidesurface and a second inside surface;

a fiber opening roll rotatably mounted in said housing, said roll havinga clothing peripherally disposed thereon within said first insidesurface to define an annular duct and a peripheral surface at at leastone side of said clothing to define a laterally extending pneumaticsealing clearance with said second inside surface of said housing.

21. In an open end spinning device as set forth in claim 20 wherein saidsealing clearance is of a radial size of from 0.3 millimeters (mm) to0.5 millimeters (mm).

22. A fiber opening roll for an open end spinning device having aclothing peripherally mounted thereon and a peripheral surface at atleast one side of said clothing extending laterally away from saidclothing, said surface having a width (b) 2 d /a'k wherein d is thediameter of said surface, a is the working width of said clothing and kis a constant of from 0.02 to 0.12.

23. A fiber opening roll as set forth in claim 22 wherein said surfaceis disposed radially outwardly of said clothing.

24. A fiber opening roll as set forth in claim 22 wherein said surfaceincludes at least one circumferential groove therein.

25. A fiber opening roll as set forth in claim 22 wherein said surfaceis conical and merges with the base of said clothing.

=l l l UNITED sums; OFFER CERTIFICATE K} RRE CTIGN Patent No. 3,800,520WM "Dated April 2, 191 1- Adoli Schiltkneehd I It is certified thaterror appamis in tha fLbfivC-"ilfiflTlI f I'm] patent and that saidLetters Pat-ant are herewy corrected as ss'nown 'hz'zluwz coilimn 4,line 21, "K 9 7/8 10G" should be Column 5 lirie 21, "agnle" should beangle- Column 5, line 57, "nothing? should be --clot hing--.

Column 6, line 3" should be 31. co1umn6, line 21, "to" should. be--into--.

Column 6, lines 62.63, "lubzr'iczatns" should be --lubricat-- Column 7,line 13 "seocnd" should be --second--.

Column 8, line 16, "swam-O11" should be --of said roll- Th priorityparticulars of the patent are omitted.

v Switzerland Patent Application 8317/72 filed June 7, 1972 to which theright of priority is claimed.

Signed and sealed this 1st day of October 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. 6;. MARSHALL DANN Attesting Officer Commissioner ofPatents FORQ! PO-IOSO (10-69) v USCOMM-DC 60373-P69 9 U.S GOVERNMENTPRINTING OFFICE I969 0-366-334,

1. In an opening end spinning device a housing having a firstcylindrical inside surface, a seocnd inside surface, a fiber feed pointcommunicating the inside of said housing with the exterior of saidhousing, a fiber transfer duct communicating the inside of said housingwith the exterior of said housing and a waste separating point betweensaid feed point and said duct communicating the inside of said housingwith the exterior of said housing; and a fiber opening roll rotatablymounted in said housing, said roll having a clothing peripherallydisposed thereon within said first cylindrical inside surface forcombing out fibers from a delivered sliver, said roll and said firstcylindrical inside surface defining an annular space for guiding an airstream under vacuum from said feed point past said waste separatingpoint to said transfer duct, said roll having a peripheral surface at atleast one side of said clothing defining a laterally extending clearancewith said second inside surface of said housing to communicate saidannular duct with a space of higher pressure.
 2. In an open end spinningdevice as set forth in claim 1 wherein said roll has a second peripheralsurface on an opposite side of said clothing defining a second laterallyextending clearance with a further inside surface of said housing.
 3. Inan open end spinning devices set forth in claim 1 wherein said clearancehas a width (b) of b > or = d2 /a .k wherein d is the diameter of saidperipheral surface, a is the width of said clothing and k is a constantlarger than 9/1000.
 4. In an open end spinning device as set forth inclaim 1 whereiN said clearance is cylindrical.
 5. In an open endspinning device as set forth in claim 1 wherein said clearance isconically diposed outwardly from said roll.
 6. In an open end spinningdevice as set forth in claim 1 wherein said clearance merges with thebase of said clothing.
 7. In an open end spinning device as set forth inclaim 1 wherein said clearance extends radially outside said clothing.8. In an open end spinning device as set forth in claim 1 wherein saidclearance extends intermediately of said clothing.
 9. In an open endspinning device as set forth in claim 1 wherein said clearance includesa plurality of laterally extending narrow zones and a radially extendingwider zone arranged between said narrow zones.
 10. In an open endspinning device as set forth in claim 9 wherein the diameters of saidlaterally extending zones are stepped.
 11. In an open end spinningdevice as set forth in claim 10 wherein said second inside surface isstepped to form said wider zone.
 12. In an open end spinning device asset forth in claim 9 wherein said roll has grooves in a rim thereofforming said wider zone, said grooves extending from the outside towardsthe inside in opposition to the direction of rotation of said roll. 13.In an open end spinning device as set forth in claim 12 wherein saidgroove forms a very small angle with respect to the lateral limitationof said roll and extends over at least a substantial part of thecircumference of said roll.
 14. In an open end spinning device as setforth in claim 12 wherein said groove forms a large angle with respectto the lateral limitation said roll and extends only over a smallfraction of the circumference of said roll.
 15. In an open end spinningdevice as set forth in claim 1 wherein said clearance is of variablewidth.
 16. In an open end spinning device as set forth in claim 15wherein the width of said clearance decreases from the outside towardsthe inside.
 17. In an open end spinning device as set forth in claim 15wherein said roll is eccentrically mounted with respect to said secondinside surface to vary the width of said clearance.
 18. In an open endspinning device as set forth in claim 15 wherein said housing has arecess of circumferentially limited extension to vary the width of saidclearance.
 19. In an open end spinning device as set forth in claim 1wherein said housing has a reduced corner space on the side of said rollopposite to the side of said clearance.
 20. In an open end spinningdevice a housing defining a first inside surface and a second insidesurface; a fiber opening roll rotatably mounted in said housing, saidroll having a clothing peripherally disposed thereon within said firstinside surface to define an annular duct and a peripheral surface at atleast one side of said clothing to define a laterally extendingpneumatic sealing clearance with said second inside surface of saidhousing.
 21. In an open end spinning device as set forth in claim 20wherein said sealing clearance is of a radial size of from 0.3millimeters (mm) to 0.5 millimeters (mm).
 22. A fiber opening roll foran open end spinning device having a clothing peripherally mountedthereon and a peripheral surface at at least one side of said clothingextending laterally away from said clothing, said surface having a width(b) > or = d2/a.k wherein d is the diameter of said surface, a is theworking width of said clothing and k is a constant of from 0.02 to 0.12.23. A fiber opening roll as set forth in claim 22 wherein said surfaceis disposed radially outwardly of said clothing.
 24. A fiber openingroll as set forth in claim 22 wherein said surface includes at least onecircumferential groove therein.
 25. A fiber opening roll as set forth inclaim 22 wherein said surface is conical and merges with the base ofsaid clothing.